3D printed hollow core terahertz Bragg waveguides with defect layers for surface sensing applications

Area of Science:

• Optics and Photonics
• Terahertz (THz) Technology
• Sensing and Spectroscopy

Background:

• Hollow core Bragg waveguides offer unique light-confining properties.
• Resonant surface sensing requires high sensitivity to detect subtle changes in material properties.
• Terahertz (THz) spectroscopy provides non-ionizing and material-specific characterization.

Purpose of the Study:

• To develop and demonstrate a 3D-printed hollow core terahertz (THz) Bragg waveguide for resonant surface sensing.
• To investigate the use of a defect layer to create a sharp transmission dip for sensing applications.
• To evaluate the sensor's sensitivity and detection limits for thin layers and powder analytes.

Main Methods:

• Theoretical modeling and experimental validation of a defect-engineered THz Bragg waveguide.
• Calibration using polymer (PMMA) layers of varying thicknesses.
• Analysis of THz resonant surface sensing with α-lactose monohydrate powder using a rotating fiber and powder feeder.
• Comparative study of time-domain spectroscopy (TDS) and continuous-wave (CW) THz systems with THz imaging.

Main Results:

• A sharp transmission dip was created by introducing a defect in the Bragg reflector, enabling sensitive detection.
• The sensor demonstrated a sensitivity of 0.1 GHz/μm for changes in defect layer thickness.
• Reliable detection of α-lactose monohydrate powder layer variations as small as 3 μm was achieved.
• Comparative analysis of TDS and CW THz systems for surface sensing was presented.

Conclusions:

• 3D-printed hollow core THz Bragg waveguides with engineered defects are effective for high-sensitivity resonant surface sensing.
• The developed sensor can detect minute variations in material thickness and properties.
• The study highlights the potential of THz Bragg waveguides for various surface analysis applications.